I don't think that City are so fed up with EPL titles that they are ready to put the Champions League higher in their priorities. Maybe if they had a guaranteed choice between these two titles, they would choose the Champions League, but there is no such choice, and even reaching the final, you can lose everything. In terms of reliability, the EPL looks much better, especially when your team is in the lead, albeit by a small margin.
Yes, Manchester City will not be bored with the Premier League title and that is reflected in how they have continued to dominate the title since Guardiola took over as coach.
I think it's true that Manchester City's main target in the Champions League is their first title, but that doesn't have to cost them the Premier League title which I think is just as important to have every season. Both titles are important to them even though they would have preferred the Champions League
"if they were given a choice". Their huge investment so far has not paid off in the Champions League with Guardiola, but they still have a chance to make it happen this season.